The subject matter disclosed herein relates generally to cryogenically cooled superconducting magnets, such as for magnetic resonance imaging (MRI) systems, and more particularly to systems and methods for insulating a cryogen vessel or a thermal shield for the superconducting magnets.
In superconducting coil MRI systems, the coils forming the superconducting magnets are cryogenically cooled using a cryogen vessel, typically a helium vessel (also referred to as a cryostat). During certain operating conditions or transfer of the MRI systems, generated heat can overheat a localized area of the coil and create a normal zone, where the conductor loses the superconducting property and transfers to a normal resistive state. The normal zone will spread through the coil due to the Joule heat and the thermal conduction, which results in a quench event. The quench is accompanied by the rapid boil-off of helium escaping from the cryogen bath in which the magnet coils are immersed. Each quench, followed by the re-fill and re-ramp of the magnet, is an expensive and time consuming event. Accordingly, cooling and insulation systems for MRI systems are used to minimize the likelihood of overheating of the superconducting magnet coils.
For example, the cryogen cooling system of some of these MRI systems include a cryocooler, such as a coldhead within a coldhead sleeve that operates to recondense vaporized cryogen to continually cool the superconducting magnet coils during system operation. Additionally, thermal insulation may be provided around the helium vessel to insulate the helium, such as from external thermal radiation or other forms of heat transfer into and out of the helium vessel. However, in order to provide the insulation or increase the thermal insulation properties of these conventional thermal insulations, additional thermal layers or costly modifications are needed.